Force a mac to use a specific email client (Thunderbird)

can you not uninstall mac mail? You've followed the instructions @ http://osxdaily.com/2014/05/06/change-default-mail-app-mac/

I didn't try to uninstall macMail. I'm not sure it's possible or not. Since everything is so tightly integrated I didn't give it much of a thought.

Yes, I have followed the instructions as listed on the website you referenced. It's definitely set up with Thunderbird as the default email reader.

FYI: my preference would be to not remove macMail as they are using it for a reference to an old email account.

Apple has the answer.  You have to open preferences is mail.app to change it. https://support.apple.com/en-us/HT201607

Change your default email app

    Open Mail.
    Choose Preferences from the Mail menu, then click General. Or, if you're prompted to set up an email account, add your account, then choose Preferences from the Mail menu.*
    Choose your email app from the ”Default email reader” pop-up menu.

from the apple website:
Change your default email app
Open Mail.
Choose Preferences from the Mail menu, then click General. Or, if you're prompted to set up an email account, add your account, then choose Preferences from the Mail menu.*
Choose your email app from the ”Default email reader” pop-up menu.
* You can also set your default email app in the preferences of your third-party email app.

I have done this and it still doesn't open from within the practice management software. I checked with the software company and they use the Apple defaults. Are there files that need to be associated with the program (thunderbird)? I'm wondering if it's not just a default issue but there are other associations in place. Do you know what extensions I'd be looking for that would be associated with sending email?

I think you're actually stuck with this one .. it may be the case that the Application you're using has hardcoded a call to APPLE MAIL and not just any Mail App.  If that's the case then you cannot override it in the System Preferences or Apple Mail Preferences.

You might want to question the developers of the practice management software as to how to override it .. or even if it is possible.

Clicking a web-based mailto: link should open Thunderbird ... if that works then you know that the problem lies with the practice management software and not the other settings.

Sorry for the long time on the reply. I didn't see an email notice come through. I think you're probably right about the hard code in the software.  I did contact the practice management developers and they insist that they don't have anything hard coded for that and rely on the Apple's defaults. If that were true, I'd really expect it to work or at least have someone chime in that they encountered the same problem. Haven't see this anywhere on the web.

Did you confirm if a browser based MAILTO link works and opens Thunderbird?

No, I'll need to check that out. Thanks for the hint. I'll check it today as I'll be onsite.

Eoin,

I tried the mailto check and it did open in Thunderbird. Do you think that this means that's it's hard coded into the Practice Management System?